Vascular diseases such as coronary heart disease, atherosclerosis, stroke, restenosis, and peripheral vascular disease, remain the leading cause of death and disability throughout the world. About 1.5 million people die each year in the United States alone from myocardial infarction resulting from congestive heart failure. While diet and life style can accelerate the onset of vascular diseases, genetic predisposition leading to dyslipidemia is a significant factor in vascular-related disabilities and deaths. "Dyslipidemia" means abnormal levels of lipoproteins in blood plasma.
Several risk factors have been associated with increased risk of vascular disease. Among these are the dyslipidemias of high levels of low-density lipoprotein (LDL), and low levels of high-density lipoproteins (HDL). The ratio of HDL- to LDL-cholesterol is often used to assess the risk of vascular disease. A high ratio of HDL/LDL cholesterol is desirable. Compounds that increase this ratio by either lowering LDL or increasing HDL, or both, therefore, are beneficial. Recent studies have also shown that elevated levels of lipoprotein(a), "Lp(a)", are detrimental.
Lp(a) appears to be undesirable, since elevated levels of Lp(a) have been associated with the development of atherosclerosis, coronary heart disease, myocardial infarction, stroke, cerebral infarction, and restenosis following balloon angioplasty. In fact, Lp(a) appears to be an excellent predictor for stroke. Accordingly, high concentrations of Lp(a) is one of the major risk factors leading to death from heart disease.
Lp(a) is composed of LDL and a high molecular weight glycoprotein called apolipoprotein(a), apo(a). Epidemiological studies show that, when present in high levels in the plasma, Lp(a) is an independent risk factor for premature atherosclerotic coronary heart disease. A concentration of 0.30 g/L in plasma is considered to double the risk of premature coronary heart disease and has been used as a clinical set point to determine what plasma concentrations of Lp(a) are considered above normal and for which treatment to lower plasma Lp(a) levels may be desirable.